321 stainless is DOUBLE the price of 304L. That's why nobody uses it. Only high end automotive or aircraft suppliers carry it as well so it's fairly difficult to find materials in the bend/size you want without going to specialty shops that like to tack on 20% just because it's them selling it.

304L on the other hand can be found in about a thousand different sizes and from hundreds of suppliers.

I don't disagree though, 321 is definitely a more preferable material then 304L. But if cost was no issue and we all used the proper materials, all of us should be using Hastelloy/Inconnel because even 321 still isn't rated for the temperatures and exhaust manifold actually sees in use.

As for ID sizing, 1.25" schedule 10 pipe (1.44"ID) has been proven to make more midrange and improve spool on the 4G63 over the 1.5" pipe. The 700HP/8500RPM range is where it starts to be an issue. To match the EVO port, you actually need roughly a 2"ID pipe to reach the perimeter sizing, flow wise though, I think it's around 1.8"ID area.

My preference though is in the 1.5-1.625"ID range but with a bend radius no tighter then 2.5". When talking pipe flow, bend radius has a bigger impact then almost anything else.

 

x622 very nice S2000!

What turbo are you running?

 

EFR 9174 w/ 1.05 AR housing and a quick spool valve.


Also, as for 321 being double the cost, and? A builders kit for a manifold is now $250 instead of $125. I fail to see what your point is. (A kit consisting of 16 bends -- 12 long radius and 4 short radius, and 4 foot of straight)


As for port size, you can always do what I did. If you look closely at my head flange, It's ports are taper matched to the ID of the pipe I'm using.

 

actually, on my manifold the difference in material cost between 304 and 321 is about 50 USD... but I did find good source of 321.

As for tubing size..
evo exhaust port is 1412 mm2, T4 ports are 1614 mm2 each.

my tubing, 48.3x2.6 mm is 1.69 inch ID, and 1458 mm2.... for me this is ideal from what is available. Also, bend radius is 2.25 inch, and when I stretch and ovalize the end of the tube to match the port, I get a nice transition that is between 2 and 3 inches long... which is far better than 1/2 transition on some manifolds that do it all in the flange, small runner manifolds included.

As for turbo lag, it is also a factor of runner length and overall volume, and that is why I tried to keep it short, with 380 mm / 15 inch runners. The proof is in the pudding though.. will have to wait a bit for that..

 

I am super impressed with the 7163 again-

we just finished a kit for the subaru platform- single scroll internally gated- and STOCK location- feeding through a stock airbox/intercooler and catted on 93-

the car went from 298/310 on the stock turbo 19psi - to the 7163 kit at 22 psi- and picked up 100whp and 80wtq with about a 350 rpm loss in spool-

such great turbos-

cb

 

$50 is definitely worth it if that's what you are getting it for. I've done a lot of pricing out 321 though and 304 mandrel bends (and even straight tube for that matter) is 1/2 the price. In fairness though, the 321 bends are almost always better quality bends. Comparing to equal quality bends in 304, the difference is a lot less. I tend to buy high quality material bends that have more ovalization then the high end bends.

Port size, it has been a long time since I measured it out. That larger 1.8" figure might have also been after porting. As for the transition, when converging (side of runner) you can actually throw in a 30* angle without flow separation. The top and bottom transitions that are divergent tapers on the other hand need to be much more shallow to avoid separation. No doubt though, spreading it out over a couple inches is superior. It also helps keep charge velocity high at the valve which should reduce reversion.

 

So with that knowledge - would a 7163 with Twin Scroll internal wastegate be similar boost threshold as a factory Subaru turbo?

 

Yeah, I was surprised at the 321 price. Looking at it earlier, at burnsstainless I was shocked, but it seems that the 321 has become popular in industrial use, and can be bought as a normal 90 deg weld elbow with no extra premium from industrial steel sources. At least over here in the EU... having said that steel prices are volatile.
In the end I went with 316Ti for the flanges and 321 for the rest.

I made a test piece where all the transition was done in the 18mm thick flange and then out to my 48.3 mm dia tubing. I agree with you that it can be done and is so much easier to make, but I prefer the ovalized and stretched tubing on the flange. It is a pain to make, makes life difficult on the rest of the manifold due to misalignment of the tubing when bending, but I feel it will be worth it.

 

NEVER go by burns stainless. They are easily double what everyone else is even though they are just reselling coastfab stuff. Quite frankly, I don't understand how they can get away selling at the prices they do. There are a ton of other suppliers that deliver just as good or better products for under half to a third of the cost that they sell anything for.

 

Agreed... once you start shopping around smartly you can get all sort of great deals..
Stainless bends are industrial things and should be bought there.. However, there are some very specialized places that can bend tubing in all sort of radiuses, and from nice materials like inconell, but those are way out of my budget.

Recently I took the risk and for my friends evo 9 build using a hks 7460KAI turbo I went with a really dirt cheap tube and fin IC, quite probably made in china and sold by Boost products in europe...

Anyway.. the thing works great and I have temp logs, not just the feel.... I just got one for my build now and they even improved the core design this year..

After some more work on the prototype and thinking about making my life simpler with transitions in the flange I decided on sticking with the original design but with improved flange.. Ovalized transition works great even with the worst possible scenario of ovalizing the bend..

 

Huh...
Maybe the transition doesn't matter???

 

Has anyone used the Driven Fav EFR Turbo Kits? I really want to go this route with my turbo upgrade. They sell a lot of great products I have purchased from them

 

HOLY CRAP.

That's hilarious lol

I had to stop watching it though. I didn't have the heart to watch them hurt the headers anymore.

That actually makes me think the dent in my downpipe really isn't hurting anything.

 

LOOL

on one of my winter runs I managed to hit an armco and take off a part of my bumper... on the return I got a feeling that the car was missing some power.. (yeah, I continued to push on.. smart)... so I take a longer look and see that the IC pipe is crushed to maybe 20% of its former crossection... hahaahahaa

 

Downpipe mock up...




We will run twin flex pipes on the DP, just like what we did for the stock frame turbo car done last summer..



I found it greatly reduces the loads on the turbo and manifold as the flex points are where they should be for the normal engine movement..